The technique of using a laser beam (such as a semiconductor laser) to read data recorded in a read-only optical recording medium (such as a CD or DVD) is well known in the art. The laser beam is focused on the track on the surface of the optical disc through an objective lens located in an optical pickup head, and a photo detector is then used to transform the return light reflected from the optical disc to regenerated signals so that the data recorded in the optical disc may be retrieved. During the data reading process, a tracking signal, focusing signal and radial tilt signal also have to be retrieved from the return light. The tracking signal and the focusing signal are used to control an actuator to move the objective lens in the optical axis direction (i.e. focusing direction), optical disc radial direction (i.e. tracking direction) and radial tilt direction so that the laser beam can accurately focus on a preset track on the optical disc surface.
While control of the radial tilt direction is not necessary in the reading operation of the read-only optical recording media, it is mandatory when the laser beam is used to write data on the writable optical recording media to control writing accuracy. The known technique at present for this purpose involves using an actuator that contains a plurality of coils on an objective lens bracket (or other elements), or forming a plurality of coils on a printed circuit board attached to an objective lens bracket to control the moving directions of the objective lens. Whatever designs are adopted for the coils, the locations of the coils are the same.